Add __unix virtual package as dependency
Add __unix virtual package as dependency

Prevent installation on windows as it's not compatible

conda-forge/staged-recipes,johanneskoester/staged-recipes,jakirkham/staged-recipes,ocefpaf/staged-recipes,goanpeca/staged-recipes,conda-forge/staged-recipes,goanpeca/staged-recipes,jakirkham/staged-recipes,johanneskoester/staged-recipes,ocefpaf/staged-recipes